Method and apparatus for making fibrous light-conducting devices



METHOD ANH M'mRATUs von MAKING FIBROUS LIoIiT-CONDUCIING max/[mns Dn X s G E T m R U C Ma mnu... F E T U .I.. Tl S 6 S G QJ 1 2, 2 um e F 5 Sheets5l1eet 1 Filed Dec. 19, 1960 L. E. CURTISS Feb. 22, 1966 5 Sheets-Sheet 2 Filed Dec. 19. 1960 Feb. 22, 1966 L E, Cum-|55 323631@ METHOD AND APPARATUS FOR MAKING FIBRUS LIGHT-CONDUGTING DEVICES Filed Dec. 19, 1960 I 5 Sheets-Sheet 5 Feb. 22, 1966 L E Cum-|55 3,23,Y

METHOD AND APPARATUS FDR MAKING FIDRous LIGHT-counucwm DEVICES Filed Dec. 19. 1960 5 sheets-sheet 4 Feb. 22, 1966 L.. E. CURTISS 3,236,730

METHOD AND APPARATUS FOR MAKING FIBROUS LIGHT-CONDUCTING DEVICES Filed Dec. 19. 1960 5 Sheets-Sheet 5 s fidarti 3,235,710 Patented Feb. 22, 1966 3,236,710 METHOD ANI) APPARATUS FOR MAKING Ftlii-OUS LIGHT-CONDUC'IING DISv'lCIES 0 Lawrence E. Curtiss, New York, NX., assignor of thirtythree and one-third to Basil I. Hirscliowitz, Birmingham, Ala., and thirty-three and one-third to Wilbur Peters, Ann Arbor, Mich.

Filed Dec. 19, 1960, Ser. No. 76,868 19 Claims. (Cl. 156-167) This invention relates to a method and apparatus for manufacturing light transmitting devices of the type which comprises a large number of elongated transparent fitaments or fibers of extremely small diameter arranged in a bundle so as to transmit light or an image from one end t0 the other end of the fiber bundle. More particularly, the present invention relates to an improved method and apparatus for making such liber optic devices at high speed and with enhanced precision.

The transmission of light or optical images by means of a bundle of a multiplicity of very thin transparent fibers as distinguished from conventional lenses or mirrors has long been known. However, considerable difficulty has been encountered in making devices of this class. This may be better appreciated when it is understood that the elongated transparent fibers may each be as small or smaller than .00L inch in diameter. Furthermore, as is brought out in the copending application of Lawrence E. Curtiss filed on May 6, 1957, Serial No. 657,325; each fiber, to ensure efficient light transmission, includes a core formed of a glass having one index of refraction and a uniform coating over the entire surface of the core having an index of refraction which is lower than that of the core. Each of the fibers should be substantially uniform from end to end and, while exceedingly flexible, must be handled carefully both during the formation and after the formation of the bundle to avoid breakage. For some purposes substantially rigid bundles may be formed while for others a high degree of. flexibility intermediate the ends ofthe bundle may be provided.

The ber optic bundles may vary widely both in length and in diameter or width depending upon their ultimate use, for example, the length ofthe bundles may vary from a few inches to a yard or more and there may be as many as 100,000 or more individual coated fibers in a bundle having a cross sectional area of about one-half inch square.

The fiber bundles may be used to conduct light or an image or they may be utilized as both light and image r conductors. ln either case, it is necessary to minimize the occurrence of defects which tend to reduce the light conductance of the fiber or the bundle made therefrom from one end to the other, particularly as the length of the device is increased. In addition, in the case of an image conductor, it is necessary to provide a highly accurate alignment of the opposite ends ofthe fibers. For example, the objective ends of the fibers receive light from the field depending upon their mutual orientation and if the same mutual orientation is faithfully maintained at the eye piece end of the device the image is conducted without loss in resolution which would result from misalignment of the fibers at one end relative to their opposite ends.

One problem encountered in the manufacture of such devices involves the difficulty which has been experienced in maintaining the width ordiameter of the fiber constant during the drawing process. For example, in the method brought out in said copending application, a glass rod having the desired index of refraction for forming the core of the fiber is mounted within a tube of a glass having an index of refraction desired in the coating so that both may be simultaneously heated to a temperature at which a fiber having a core and a coating of the desired composition and thickness may be drawn therefrom. The material forming the core is di'awn from the central rod and the material forming the coating is simultaneously drawn from the tube surrounding the rod. ln practice the diameter and uniformity ofthe drawn strand are largely governed by the temperature of the two glasses from which the strand is drawn, the rate at which the glass rod and tube are fed to the heated zone, and also the rate at which the liber is drawn. When all of the factors are properly balanced, a supply of the two glasses is provided at the drawing point at the proper state of fluidity to permit the drawing of the desired constant diameter strand. Simultaneously as this .supply is formed it is diminished by the withdrawal of the strand and replenished in accordance with the rate at which the tube and rod are advanced to the heating area or furnace. interruptions or variations in the rate at which the strand is drawn are undesirable because of the resulting adverse effect upon the dimensions and uniformity of the drawn fibers.

Another problem which has been encountered in the manufacture of glass liber bundles for use in the transmission of-light and images, resides in the difficulty of applying the required degree of tension to the glass liber as it is being simultaneously drawn from the molten supply land wound about the periphery of the rapidly rotating winding drum. In drawing and winding the fiber about the drum to form the successive layers, if the ber forming any one layer is not in tight engagement with the surface of the drum or an underlying layer, it may become disarranged duc to thc disturbing forces which are generated by the cumulative effect of the next succeeding layers. The lvery small diameter fibers utilized do not have sufficient tensilesstrength to withstand the tension required to provide the desired tightness of the various layers. ln practice it has hitherto been found to becxtremely difficult to wind the multiplicity of layers about the winding drinn with a satisfactory degree of tightness while at `the same time avoiding breaks in the glass fiber.

in addition to the difliculties encountered in winding the drawn glass fiber with suflicient tightness about the winding drum, it hns also hitherto proven to be exceedingly difficult, if not impossible, to maintain the required degree of precise alignment of the opposite ends of the fibers during the subsequent stages of manufacturing an image conducting device. While some small amount of misaligiiment may be tolerated, the magnitude of this problem may be better appreciated when it is understood that with fibers having a diameter of about .O01 inch, misali-gnment of the` individual fibers as small as about .0005 inch is objectionable for many uses.

Breaks in the glass fibers are undesirable as may be readily appreciated in vicw of their delcteriouscffect upon the efficiency of light and image transmitting devices. The presence of a break in the glass fiber on the winding drum has a further and aggravated effect because of the speed of rotation of the drum. Under the influence of centrifugal and air turbulence forces, loose ends resulting from breaks in the liber are carried away from their intended position in the layer being wound and ultimately are often trapped in such manner that they extend across the turns of the liber around the drum. This results in the formation of irregularities such as bumps and depressions which often have a magnified effect as successive layers are formed.

It is therefore a principal object of this invention to provide an improved method and apparatus for manufacturing light and image transmitting glass liber bundles at high speeds and having markedly enhanced light and image transmission capabilities.

Another object is to provide such a method and apparatus by means of which such light and image transmitting fiber bundles may be manufactured with adjacent strands in exceedingly tight juxtaposed relation as is especially desirable at the ends of a liber bundle.

A further object is to provide such a method and apparatus by which liber bundles may be `readily formed Vat high speed substantially free from the deleterious effects of broken fibers.

Another object is to provide glass coated glass fiber bundles characterized by improved light and image transmission as well as enhanced ruggedness.

The foregoing, as well as further objects and features of the present invention, will be apparent from the following detailed description and the accompanying drawings in which FIGURE 1 is a front elevational view of a preferred apparatus for carrying out the method of the present invention;

FIGURE 2 is a side elevational View taken from the point of view of the line 2-2 in FIGURE l;

FIGURE 3 is an end view of an enlarged scale of a portion of the winding drum shown in FIGURE 1;

FIGURE 4 is a perspective view showing the wound glass liber layers after removal from the winding apparatus;

FIGURE 5 is a perspective view of an optical glass fiber bundle, partially broken away for convenience;

FIGURES 6 and 7 are perspective views of apparatus useful in simultaneously drawing and winding a plurality of glass fibers;

FIGURES 8 and 9 are perspective views showing a combined light and image conducting optical glass liber bundle in different stages of manufacture; and

FIGURE 10 is a perspective view of another form of optical glass fiber bundle.

The method of the present invention isapplicable to the manufacture of light-or image transmitting liber bundles by drawing ot both a single composite glass fiber strand or two or more ot such fibers and simultaneously winding the fiber` or fibers about a winding drum. The present invention will be first described in connection with the making of a bundle of light conducting glass fibers by drawing a single composite glass ber having a fiber glass core of one refractive index and a relatively thin glass coatingvuniformly fused over the entire outer surface of the core, the coating being formed of a different glass having a lower index of refraction than the glass fiber core.

As brought out in said copending application, a rod of optical glass having the requisite properties for forming the light conducting core of the composite glass liber is surrounded by a tube of optical glass having a lower index of refraction than the glass forming the core. The glass rod and the surrounding lglass tube are heated to thc temperature at which a uniform composite liber may be drawn therefrom, the core of the fiber being drawn from the glass rod simultaneously as glass from the tube is drawn so as to form a uniform coating over the entire surface of the core. This composite liber which is lirst drawn from the glass rod is attached to a slowly revolving winding drum. The winding drum, once the fiber strand has been attached to it, is gradually brought up to normal windini'` speed. The initial turns of the glass liber around the wic'ing drum are formed in a discard region and the winding of the desired layers of glass fiber about the drum is not commenced until the apparatus has been in operation long enough for the formation of the glass fiber to be stabilized at the desired diameter. When thc formation of the glass liber is stabilized, the fiber is progressively advanced along the drum so that the turns of the liber are formed about the winding area of thc drum. As the winding operation continues the liber is fed to the drum with the required amount of advance to lay down a solid layer with the adjacent turns in tightly juxtaposed relation. When the winding area of the drum has been covered with the liber turns, to form a layer having the desired axial width, the liber being fed is advanced axially so as to be laid down onto a discard area of the drum which is beyond the winding area in the direction of advance.

In order to insure that the turns of the glass liber form a smooth, tightly packed layer about the winding drum, the length oli' glass ber forming this first layer may be wet by suitable liquid. lt has been found that with thc extremely thin diameter liber which is formed and handled in carrying out the present invention, the surface tension ot the liquid with which the fiber is wet exerts sufficient force to cause the liber to lay in place on the surface of the winding drum. For this purpose, the liquid utilized should be nonreactive with the material forming the surface ot the winding drum and also should not react undcsirably with the materials subsequently utilized in processing the glass ber layers. A liquid such as acetone which is volatile and it present merely forms a nonreaetive diluent of the resin or cement which is subsequently applied to the glass liber layers has been found suitable.

Instead of wetting the liber strand forming the turns of the lirst layer about the drum with a volatile liquid such as acetone, the surface of the tirst layer, after it has been laid down and before covering it with the turns forming the second layer, may be coated with a suitable liquid which serves to anchor the turns of the fiber forming the layer.

Assuming that the first layer was laid down by advanc ing the successively formed turns of the fiber from left to right axially along the winding drum, then for those uses where the registration and alignment of the libers are not especially critical, the second layer may be laid down by advancing the fiber turns in the opposite direction, that is, from right to left, When this procedure is followed, alternate layers have a right-hand pitch while the remaining layers have a left-haud pitch and thus the fibers ot t adjacent layers cross one another but at a relatively small angle. A

When the fiber bundle is to be utilized for transmitting images and particularly when such a device is formed from a single fiber which is wound to form the successive layers about the winding drum, it is preferable to form all of the layers about the winding drum with the same direction ol advance. This is accon'iplishcd by returning the fiber at the completion of cach layer lo the starting region of the drum and during this return movement ol the liber it is kept lrcc ot the winding drum. It will he appreciated that any change n the rate at which the fiber is drawn from the hot glass supply causes a change in the conditions governing the diameter of the liber being drawn drum the fiber is attached thereto at the starting discard area and winding of the next layer is carried out. As before, the surface of the newly formed layer is coated with a suitable material in order to anchor the same to the underlying layer. This procedure is carried out until a sufficient number of layers have been laid down about the winding area of the drum to provide a total thickness of glass corresponding to one of the dimensions, to the width, of the liber bundles which are to be formed.

lf desired, the liber drawn during the aforementioned retrograde movement may be utilized to form the successive layers on a second winding drum disposed alongside of and parallel to the first winding drum. In carrying out such an arrangement, thc end region of the layers on the first drum is abreast of the start region of the layers on the second drum. Thus, upon the completion of a layer on the lirst drum, the liber is transferred to the second drum and then advanced axially relative to it to form a layer. The advance of the fiber relative to the second drum is in the return direction with respect to the first drum so that on completion of the layer on the second drinn the fiber is once again in position to be attached to the first drum for the laying down of the next layer thereon.

Preferably the return of the liber from the end of one layer to the start of the next succeeding layer is carried out by attaching the liber to a return roll having a diameter which is many times smaller than that of the winding drum and which is driven directly from the winding drum at a peripheral speed which is equal to that of the winding drum. This makes it possible to lay down sticeessive layers in a more rapid sequence and facilitates maintaining the drawing speed constant.

The material utilized for coating the glass liber layers may be any one of several resins or ccments commercially available, such as epoxy resins.` The resin or cement is preferably one which doeshot set so rapidly that it will prevent the fiber ofsuccceding layers from being drawn into close, tight-packed relation with the fiber of a preceding layer. it should set sufficiently in the time required to lay down about four layers to provide a sufiieient anchoring effect so that successive layers deposited thereafter will not cause shifting of the liber turns of the underlying layer. The material should be susceptible of being applied to form a coating which is thin relative to the thickness of the glass coating which is fused to the glass' core ot the liber. A coating having a thickness as initially applied of about one-tenth the diameter of the glass fiber has been found satisfactory. An epoxy resin which has been found suitable is that sold under the designation Bond Master E-62l by Rubber it Asbestos Corp., Bloomfield, New Jersey. This resin is diluted sufliciently with a solvent so as to provide the aforementioned setting rate.

The anchoring material is applied, as by spraying, in such condition that its viscosity does not prevent but facilitates the fiber turns being drawn into the desired tightly packed relation. The anchoring material is forced from between the fibers, where they are brought into substantially tangential contacting relation, and into the small voids left open between the round bers.

The anchoring material applied to the successively wound layers of liber provides important advantages not only in minimizing the deleterious effects of breaks in the glass fiber and in serving to anoehor the turns against displacement while it is being wound but also in connection with the removal of the fiber layers from the winding drum and in their subsequent handling. As the various fiber layers are wound on the drum the anchoring material sets progressively from the drum outward. When the layers are to be rcmovcd'from the drum they and the multiplieity of individual liber turns are essentially in the form of a unitary, solid, more or less rigid ring or cylinder on the winding drum with each fiber strand joined tu it neighbors sutbstantially throughout its length. After removal from' the drum, the liber layers are in the form of a solid ring or in the form of several solid ring seetions which may be `handled without disarranging or enlangling the fiber strands.

Depending upon the subsequent processing of the fiber layers and the intended use of the fiber bundles to be made therefrom, the anchoring material may be set to such an extent that the fibers are completely immovable with respect to adjacent fibers. This is highly desirable when it is desired to produce image conducting fiber bundles in which the greatest degree of alignment and registration of the ends of the fibers are required. When light conducting bundles having lixed arcuate shapes are to be formed it may be desirable to provide a degree of set of the anchoring material which permits individual fiber strands to slide to a small degree relative to adjacent liber strands. In this condition, the liber layer ring 0r ring sections as removed from the winding drum are also essentially in the form of a solid, unitary body or bodies but are substantially more flexible.

As has been indicated, winding is terminated when a sufficient number of layers have been formed to provide a covering about the winding drtim having a thickness corresponding to the thickness of the fiber bundles desired. Then. in preparation for removing the glass from the winding drum it is cut along one or more axially extending strips from end to end. Before cutting the glass liber layers, the anchoring material is substantially completely set along the axially extending strips. In the case of a resin anchoring material it may be cured along these strips. Depending tlpon the length of the fiber bundles which are to Ibe formed one or more such axially extending strips may be prepared fur cutting. For example` if the length of the fiber bundles is to be the maximum obtainable from the particular winding drinn utilized, then the fiber layers are citt only along a single strip. lf the circumference of the winding drinn is twice as long as thc desired length of the liber bundles, then the layers are cut along two strips 180 apart. Various lengths may be obtained by cutting along strips properly spaced about the cireumi ference of the winding drinn.

When the aforementioned epoxy resin is utilized as the anchoring material it is preferably cured so that it polymcrizcs along the axially extending strips where these layers ai'e to be cut and is set substantially without polymcrization between thcse strips. lf desired the resin may be cured throughout the extent of the layers although this may make it more difficult to remove the resin from the fibers where desired.

Assuming that the liber layers have 4been cut along two strips 180 apart, two substantially solid half rings or cylinders of glass layers are obtained with the fiber strands substantially rigidly set in place. The half rings of the glass liber layers are now slit circuinfercntially to form individual liber bundles having the desired width, cach bundle being held intact by the set and/or cured resin. These strips of liber bundles are now treated to remove thc anchoring material from all but its end sections when it is desired to provide liber bundles which are flexible intermediate their ends. For this purpose, all but the end portions may tbe immersed in a suitable material which serves to dissolve the anchoring material. When the anchoring material is an epoxy resin, a suitable agent for this purpose is a solution ol` sulphurie acid heated sufficiently to dissolve the resin. This serves to free the individual ftbers'cxcept for the bonded end portions thereof. After neutralizing such reagents as may remain on the glass fibers and washing the same, the bundles are dried.

The end faces of the bundles are optically polished to provide suitable faces at the ends of each of the glass fibers. Polishing of the end faces may be carried out whenever convenient, as for example, before removal of sesamo the anchoring material or afterwards, or even after the fibers have been lubricated as will now be pointed out.

It will be appreciated that the glass fibers are relatively fragile, and when the flexible bundles are manipulated adjacent fibers are brought into contact with. each other and are rubbed one against another. Both, in order to facilitate manipulation of the bundles and also to protect the individual fibers, alubricating fluid or substance which may be any suitable oil is utilized. When, as will he described, the fiber bundle is to be encased in a covering of latex then a silicone oil is preferably used. applied by imnicrsing the unbonded portions of the fibers preferably in the oil after the fibers have been washed and dried. Care is taken to avoid the formation of only a thin film of the lubricant on the glass fibers because in that event the surface tension of the oil `may result in the extremely thin fibers being held together so thatthe flexibility of the fiber bundle is reduced and the likelihood that fibers may be broken is increased. Such difficulties are avoided by enclosing all but bonded end portions of the fiber bundle in a fluid tight exiblc enclosure, such as may be readily formed from latex which is filled with the oil to such an extent that the loose fibers float" in the oil.

Turning now to FIGURES 1-3, an embodiment of the process of this invention will now be described in connection with a preferred apparatus for carrying out the same. A solid glass rod 1() which may be about l yinch in diameter extends within a glass tube 11 and both are fed axially along through an electrically heated furnace 12. While the arrangement shown in said copending application may be utilized, uniform results may be more readily achieved when provision is made as in the present instance, for adjusting the relative rate of feed of the two glasses. For example, where the ratio of the thickness of the glass coating to the diameter of the core of the fiber 30 is equal to the ratio of tlie thickness of the wall of tube 11 to the diameter of rod 10 and both ratios are about A5, the tube 11 and the rod 10 may be fed at the same rate. Because the required thickness of the glass coating is a constant independent of the fiber size, the proportion of coating glass from the tubing may be adjusted by increasing or decreasing the rate of feed of the tube relative to the rod depending upon whether the tube wall thickness is less or greater than the value for which the rates of feed are equal. Thus, the glass rod 10 and the glass tube 11 are advanced independently by a pair of threaded shafts 13 and 14 driven through an adjustable differential drive 15 which is in turn driven by a variable speed f motor 16 through a suitable reduction gear box 17. The glass rod 10 is clamped in a collar 2f) on the end of an arm 21, the opposite end of which carries a collar 22 which releasably engages the threaded portion of the shaft 13. A bevel gear 23 fixed to the upperV end of shaft 13 engages a bevel gear 24, 'which is in turn xed to the output shaft 25 extending from one end of the differential drive 15. Suitable bushings and supports (not shown) are provided as required. A clamp 26 facilitates releasing collar 22 from engagement with the thread of shaft 13 so that the arm 21 and the glass rod 10 supported thereby may be positioned as desircdrelative to the furnace 12 at the start of operntii'in.

A similar arrangement `of parts is provided for supporting glass tube 11 from shaft 14 and for driving the latter, which parts for simplicity have been designated by corresponding reference characters with a prime added. Thus, shaft 14 driven from the output shaft 25 of the differential drive 15, through meshing bevel gears 23', 24'. The glass tube 11 is clamped in a collar 20 carried on one end of the arm 21', the other end of which ter` niinates in a collar 22' which engages or is free to slide over the threaded portion of shaft 14 depending upon the position of clamp member 26.

'his is The iiiiss rod 10 from which the fiber core is drawn may he. formed of any suitable high quality optical glass. Taking into account the index of refraction and the softcning point of the glass forming rod 10, a high quality glass is selected for use in the tube 11 which forms the coating fused to the surface of the core of the ber 3f). As is known, the glass forming the fiber core should have a higher index of refraction than that forming the coating. While a wide variety of glasses may be utilized an index of refraction of approximately 1.68 for the core glass and an index of refraction of. about 1.52 for the coating glass provides good results although glasses having other indices of refraction may also be used. The glasses should be such that when heated as will be described with the glass 4rod 10 inside the glass tube 11, they each attain substantially similar viscosities. The coefficients of; expansion of the two glasses utilized should be the same or sufficiently matched to avoid the development of internal forces which may lead to fracturing of the fibers.

The furnace 12 is positioned so that the rod 10 and l the tube 11 may be inserted axially into its open upper end. The heater coils of the furnace 12 are connected in the conventional way through a temperature control unit 27 to a source of electrical power through contacts which respond to a temperature sensing device such as a thcrrnocouple mounted in the furance. Such arrangements are well known and a detailed description thereof is not considered necessary. Suffice it to say that the arrangement functions automatically to maintain a dcsircd temperature within the furnace.

The fiber 3l) which is drawn downward out of the furnace 12 passes through a diameter inspecting or sensing unit 23 and then over a system of pulleys, yet to be described to a winding drum 35.

Sensing unit 23 is part of a conventional fiber diameter measuring and indicating systems 29 of the type in which the fiber passes between a photeelectric device and a light source, the pbotoelectric device providing an output representative of the diameter of the fiber.

The fiber passes downward from the sensing unit 28 and partially about a pulley 31 from which it passes horizontally to a pulley 32. From pulley 32 the fiber travels vertically partially over a pulley 33 and under a pulley 34 on to the winding drum 35. When the fiber being drawn has such a low tensile strength as not to be able to withstand the drag of; the pulleys, the pulleys may be air-driven or otherwise driven to avoid breaking the fiber. When a plurality of fibers are drawn sirnulta ncously as will be more fully pointed out hereinafter the combined tensile strength of all the bers may be effective to overcome the drag of the pulleys.

As shown, pulleys 32, 33 and 34 are mounted in vertically alingned relation and are supported from a movable feed eariage 44. Pulley 32 is rotatably supported by a rigid support member 36 while pulley 33 is rotatably supported on a frame member 37 carried by the carriage t 44. While pulleys 31, 32 and 33 are mounted for op- *eration in mutually fixed relation, the pulley 3ft is.

mounted `for displacement between two positions, one in close spaced relation with the drinn 35 andthe other away from the surface of thc drum. For this purpose pulley 34 is rotatably mounted on one end of an iii'm 41 mounted to rock about a shaft 42. connected to frame member 37, between one position in which the pulley 34 -is closely adjacent to winding drum 35 and a second position, shown in broken lines in FIGURE 2, in which the pulley 34 is away from the drum 3S. A spring #t3` the frame member 37, which is adjustable to precisely position the pulley 34 relative to the winding drum 35.

The winding drum 35 is mounted for rotation on a shaft driven by a motor 46. The coupling between the shaft 45 and the motor 46 is arranged to minimize any possibility of undesired variations in the rate of rotation of the shaft. The motor 46 is connected to the electrical supply through a variable speed controller and indicator 47 by means of which the output speed of rotation of the motor shaft and in turn the speed of rotation of the shaft 45 may be precisely controlled from start up to normal operating speed.

Fixed to shaft 45 for rotation therewith is a gear wheel 4S which serves to drive a gear wheel 49 fixed to feed screw 50 through a gear train indicated generally at 51 which includes a variable gear box 52 by means of which the rate of rotationof the feed screw 5t) maybe varied in relation to the rate of rotation of the shaft 45.

The feed screw 50 extends parallel to the shaft 45 and supports the carriage 44 which is mounted to slide along a railv 44'. Any one of the various well known arrangements may be provided in the carriage 44 so that it is traversed to the right or left relative to thc drum 35 (as viewed in FIGURE 1) depending upon the position of a selector handle 53.

The winding drum 35 comprises a cylindrical shell 55 secured to and supported on radial members or spiders 56 provided with axially disposed hubs 57 (FIGURE 3) by `means of which the drum is fixed to the shaft 4S. The outside surface of the shell is coated with about a one-half inch thick layer 58 of resin huilt up with layers of porous material such as an open weave fabric. The outer portion of the resin layer 53 is free of the porous material so that the surface thereof may be precisely shaped to form a cylindrical surface. The winding drum as thus formed with the resin coating 5S has unexpectedly heen found to greatly facilitate the winding of the glass fiber with the required precision as compared to a drum having a metallic winding surface.

The resin layer 58 provides a good heat barrier which facilitates heating the resin anchoring material coating the glass layers laid down thereon where it is desired to cut the glass layers in order to obtain fiber bundles of the required length. For this purpose heating elements 59 are readily imbedded on the surface of the resin layer 53. Heating elements 59 are shown exaggerated in size in the drawing but are preferably of relatively small thickness, about 0.(l0l, and are readily pressed into the surface of the resin layer 58. When it is desired to accelerate the curing of the resin coating the fibers of the layers wound on the drum, the heating elements 59 are connected to a suitable electrical power supply while winding drum 35 is either stationary or rotating. Temperaturercsponsivc thermocouples are positioned with each of the sets of heating elements 59 spaced around the periphery of the resin coating 58 and are connected to a suitable temperature controller (not shown) which governs the supply of electric current to the heating elements 59.

As has been indicated, the glass fiber 30 is threaded under the spool 34 to pass onto the surface of the winding drum 35. The latter is driven clockwise as viewed in FIGURE 2 and a freshly wound turn of the glass fiber is carried on the drum to where it is exposed to a spray of anchoring material from sprayer 62. Sprayer 62 is connected to and is movable with carriage 44 by means of a support arm 63. The sprayer 62 communicates through pipe 64 to a metering unit 65 which in turn communicates through pipe 66 with a source 67 of liquid resin in the present instance and through conduit 68 to a supply of air under pressure (not shown). lf desired, the metering unit may be linked with shaft 45 so as 4to be driven in step with the rotation of drum 35 to supply the desired amount of resin in the form of a spray. Preferably the metering unit 65 is electrically driven and is adjustable to provide the desired concentration of resin in the spray at a rate conforming to the speed of rotation of the winding drum 35.

In operation, as each turn of the glass fiber is being wound on the drum 35, it is carried past the sprayer 62 where a thin film of the resin is applied thereto and as the drum continues to rotate, the resin coating of this turn and the turns previously wound air dry to increase its viscosity sufficiently to provide the desired anchoring effect'. it is to be noted that the nozzle 62' ofthe sprayer is small and is positioned to direct its spray locally upon only a small number ofthe glass ber turns. Being movable with the carriage 44, the sprayer 62 stays in alignment with, the advancing edge of the ftoer layer being formed and continually coats the same with the desired resin hlm. Thus, the already formed portion of the fiber layer gradually emerges from the sprayed zone and the air has its full drying effect on the previously deposited resin. i

Preparatory to winding the glass fiber, the surface of the winding drum 35 is covered over the entire winding zone with a suitable release material. Fiber 3f) may be wound directly upon the resin layer 58 on thc surface of the shell 55. ln that event, the resin layer 58 is coated with grease or the like in order to prevent the resin coated glass fibers from bonding thereto. Preferably the surface of the resin layer 58 is lightly oiled and then a thin sheet 60, such as n plastic sheet of about .00O25" thick Mylar, is wrapped around the surface of the drum which serves both to protect the electrical heating elements 59 and also to prevent bonding of the fiber layers to the resin coating 58. The sheet 60 may be formed of other materials that have the required .strength as a sheet having a thickness less than that of the thickness of an individual fiber, for example steel or other metal foil may be used.

The lower ends of the glass rod 1f) and tube 1I are heated in the furnace 12 to drawing temperature. The temperature of the glass at which the drawing is carried out may vary depending upon the type of glass utilized. In any event the glass is heated short of what is considered thc start of its normal working temperature range in conventional glass practice which corresponds to a vis cosity of about lt)4 poises. In carrying out the present invention, the preferred temperature range is one at which the glass just` begins to deform under its own weight or under the influence of gravity but does not flow freely. In this condition the glass has a viscosity ranging between about and l06 poises. lt is preferred to draw the fiber 3f) with the glass of rod l0 and tube Il. in this condition because if both glasses are al a higher temperature and lower viscosity it is extremely difficult if not impossible to obtain the required optically sharp interface between the coating glass and the underlying core glass in view of the tendency of the two glasses to mix or dissolve in one another. It should be noted that while either the core glass or the coating glass may be substantially less viscous at least one of them must have the relatively high viscosity at the drawing temperature of about lfi to ttl poises. Furthermore, a difference in the viscositics of the two glasses at the drawing temperature of no more than about a factor of 10 maybe tolerated.

At the ten'iperature the fiber 30 is drawn, the lower ends of the rod 10 and tube 1t are readily tapered so that the fiber 30 may be drawn therefrom and threaded through the sensing unit 2S and past the spools 3i, 32. 33 and 34 to the drum 35. At this time, the spool 34 is retracted away from the surface of the drum 35 and the fiber 3f) is attached to the starting discard area 35a of the drum on which a film of tacky resin or other suitable adhesive is provided. The pulley 34 may now be brought to its position close to the surface of the drum 35 and the wind ing drum is brought up to normal winding speed which serves to draw the fiber at a linear speed oliabout 40 to 60 feet per second. The liber 3f! is wound about the start discard zone 35a until the indicator 29 shows that the diameter of the fiber is stabilized at t'nc dimension desired.

The carriage 44 is then advanced along the feed screw '50 so that the fiber is now laid down in turns around thc central, winding zone of the drinn and the selector handle 53 is shifted so that rotation of the feed screw 5t) serves to advance the carriage 44 along its feed slide 44 at the desired rate to form the turns of the fiber in tight side-by-side relation about the drinn with the desired pitch.

As the fiber is wound about the drum 35 to form the first and subsequent layers, the advancing end of the layer is coated with a spray of resin from the sprayer 62, which is then set by drying in the air which moves past the rotating drinn.

The laying down of the successive turns of ber to form the layer is Continued until a layer of the desired width has been formed. Thereafter, additional turns of the fiber 30 are formed about the end discard area 3511, preparatory to returning the fiber to the starting end so that the next fiber layer may be laiddown on the drum with its turns in parallel with the turns ot' the preceding layer. In the present embodiment this is carried out by transfer means now to be described in detail.

A cylindrical auxiliary roll which may be somewhat longer than the drum 35, has a diameter which is several times smaller than that of the drum 35 and is fixed to a shaft 76 rotatably supported in a C-shaped frame 77. The free ends of the frame 77 are supported on bearings 78 fixed tothe shaft 45 adjacent opposite ends ofthe drinn 35.

One end of the shaft 76 extends through the frame 77 and carries a pulley 79 driven by a belt 80 which runs over a pulley 8l fixed to the end of a short shaft 82. The shaft 82 is swingably supported from the fraaie 77 on an arm S4 and at its free end carries a wheel S3. Normally the frame 77 is positioned on its bearings 78 with the wheel 83 not in engagement with the surface of the drum 35, the arrn S4 being engaged by a latch S5.

In order to carry out the transfer of the fiber 3ft from the end discard region 35h to the start region 35a, the latch 85 is released to bring the wheel 83 into rolling engagement with the marginal end portion of the winding drum 35 whereby the wheel 83 is rotated. The rotation of wheel S3 is transmitted through shaft 82 and the belt and pulleys to shaft 76 and the auxiliary rolt 75 is thereby rotated at substantially the same peripheral speed as that of drum 35. The pulley 34 is withdrawn from the drum 35 with the result that a length of the fiber 30 extends through the space therebetween. The surface of the roll 72 having been made tacky as by spraying with resin, the frame 77 is rotated counter-clockwise, as viewed in FIGURE 2, to bring the surface of the rotating roll 75 into engagement with the fiber 30. On engagement of the glass fiber with the tacky surface of the roll 75, the latter picks up the fiber, which is now wound about the roll 75 instead of about the drum 35, and it continues to be drawn from the furnace 12 at the same constant speed as before. The carriage 44 is now shifted back along the feed screw 5t) to carry the fiber 30 into alignment with the starting discard zone 35a and, when so aligned, the pulley 34 is once again brought forward toward the tacky surface of the start discard zone 35d. This causes the length of fiber 30 between the pulley 34 and the roll 75 to touch and adhere to the tacky surface 35u. The fiber now winds about this roue of the drum 35 and the liber connected to the roll 75 is broken. The

transfer frame 77 is now shifted back to its normal rest position with the wheel 83 free from the drinn 35.

Several hundred or more fiber layers may be thus formed in succession about the winding drum depending upon 'the thickness and type of the liber bundles formed therefrom. During or upon termination of the winding operation the resin coating the fiber turns forming the multiple layers is cured by energizing the desired electrical heating elements 59.

When the selected axially extended strips have been cured the layers are cut through along these strips and the sei-:ral arcuate sections are removed from the winding drinn. In the present instance where the layers are eut along two lines 130 apart, two solid, relatively rigid half cylindrical sections 9() are formed as shown in FIGURE 4. The fibers in these half rings or shells extend circumferentially between the edges 9] and the marginal portions 92 of these fibers are bonded together by the cured resin. These half rings 9() may now be slit circumferentially to form fiber bundles 93 of the rcquired thickness.

The processing of the fiber bundles may be carried out as has been described to remove the uncured resin from the fibers intermediate thc bonded end portions 92 thereof. The loose fibers of the bundle may be inivmersed in a silicone oil in a latex sheath 94, the ends of which are secured in fluid tight relation to the projecting bonded fiber portions 92.

In accordance with a further feature of the present invention a plurality of glass coated glass core fibers 30 are simultaneously drawn and wound on the winding drinn. The process readily lends itself to the simultaneous drawing of as many as 6 or more fiber strands. Four such fibers 30a, IJ, c and d are shown in `FIG- URE 6 as being drawn simultaneously from an electric furnace which is somewhat larger than the furnace 12 previously described herein. The furnace 120 is provided with a cover 121 formed with a plurality of apertures 122 to receive and align the lower end portions of the glass rods it) and their enclosing tubes lt. These glass tubes and rods may be supported by a clarnp 123 which in turn may be mounted on the arni 2l for movement along the threaded shaft 13. in such an arrangement, all of the glass tubes and rods are fed simultaneously and at the same rate to the furnace 120. ln the event variations as in the dimensions of the various glass rods and/or the glass tubes necessitate feeding at different rates, then all of the glass rods may be fed at one speed and all of the glass tubes may be fed at another speed as was described in connection willi FIG- URE 1. Furthermore, if desired, each of the glass tubes and each of the glass rods may be fed individually and the individual feeding rates may be adjusted as desired.

While only four bers are shown as being drawn in FIGURE 6 it is to be noted that this in intended solely by way of illustration and a larger number of fibers may be simultaneously drawn. I

The fibers may all be passed through the diameter sensing head of a diameter measuring and indicating system 29 and then drawn around the pulleys 31, 32, 33 and 34 as was described in conneclion with the single fiber strand 30. For the purpose of handling such a multiplicity of fibers the pulleys 33 and 34 are provided with a plurality of parallel annular grooves which are spaced apart relatively widely as compared with the diameter of the fibers being drawn as is best shown in connection` with the pulley 34 in FIGURE 7. if dcsired, pulleys 31 and 32 may also be formed with similar annular grooves.

Drawing of the multiple fibers is carried out essentially in tlic same manner as has already been described in connection with the drawing and winding of a single fiber strand except that now the multiple fiber strands are led past the pulleys and are attached to the start winding zone 35a of: the winding drum. Each of the bers is brought into its own pulley groove and thus, on pulley 34, the fibers 30a-d ride respectively in the grooves 34a-d. attached to the starting zone 35a the pulley 34 is brought into juxtaposition with the surface of the drum and winding of the fibers in the central winding zone of the drum is begun by the fiber 39a winding a first fiber layer 125.

-The fiber 36h winds the second layer 126 over the first layer 125 and the fibers 30e and d'form the layers E27 and 128 in similar relation with the leading edge ofeach Once cach of the glass fibers has been i succeeding layer trailing behind the preceding layer by a distance equal to the spacing of the grooves 34a-r1' from cach other. As shown, a series of superposed layers are formed one on top of the other with the leading edge of an underlying layer being just ahead of the next overlying layer. In FIGURE 7, the layers 12S-128 are scen at an intermediate stage during the drawing and winding operation. Winding is continued into the end discard Zone 35!) until the winding zone has been completely covered with all of the superposed layers in the group being simultaneously formed. Then the direction of travel of the carriage 44 may be manually or automatically reversed so that it returns to the left along its feed screw Sil, laying down a second series of multiple, superposed layers ot' fibers over the winding drinn 35. The direction of motion of the carriage 44 is again reversed when all of the fibers have been carried into the start discard zone and a third set of superposed layers is laid down along the winding dliim. The carriage 44 is repeatedly traversed back and forth along its feed screw until the desired depth or number of liber layers have been formed. i

lt should be noted that during the formation of each of the superposed liber layers they are each coated with resin from the sprayer 62 as was described hereinabove. Upon the completion of the winding of the multiple fibers the treatment and processing of the glass fiber layers to form the optical fiber bundles is carried out in the same manner independent of whether they were formed by winding a single liber or a plurality of fibers. ln the formation of image conducting fiber bundles in which the'mutual relationship of the fibers at one of the ends of the bundle must be duplicated at the opposite end, satisfactory results are obtained when a relatively large number of fibers are drawn and wound simultaneously even though successive groups of the layers thtis formed about the winding drum are wound in opposite directions, That is to say, alternate groups of layers have a right hand pitch and the remaining` intermediate layers have a left hand pitch. When greater precision is desired, cach of the succeeding groups of layers may be wound in the same direction so that all of the layers have the same pitch. This maybe readily done by breaking the fibers after winding has been carried into the end discard zone 35h and then returning the fibers to the start discard zone 35a, as for example by attaching the fibers to the transfer roll 75 as was described in connection with a single fiber. ln this way, all of the layers in the winding zone are laid in the same direction while traversing the feed carriage 34 from left to right as viewed in FIGURE l.

The present invention makes possible optical fiber btindles having Widely varying dimensions and shapes. As has already been described, the liber bundles 93 as initially formed are square or rectangular at their ends depending upon the size of the strips cut from the half rings 90. When the ends of the fibers in the bundle 93 have been bonded together by means of the cured resin, the bundle may be shaped as desired, without disturbing the orientation ofthe fibers at the opposite ends, by drilling or cutting operations on the bonded portions and then removing the unwanted fibers. This is preferably carried out before the unpolymerized resin has been removed from the fibers. As will now be described in connection with FIGURES 8 and 9, a fiber bundle 93, after being separated from its parent halfa'ing 90, may be formed into a unitary concentric image and light carrier by cutting and shaping it, preferably before the set btit unpolymerized resin has been removed from the fibers intermediate the bonded end prtions 92. A tirst circular cut is made as indicated at 98 and 99 into each of the opposite end faces 96 and 97. These circular cuts extend back through the entire length of the bonded regions 92 and the fibers outside of these circular cuts are removed. These cuts `93 and 99 are carefully oriented so that the fibers within the circle of ld thc` cut 98 are also included within the circle of the cut 99. This serves to provide the exterior of the bundle of bers with a desirable annular shape. A second circular cut as indicated at ttt() and 101 of somewhat smaller diameter than the cuts 98 and 99, is made into each of the opposite end faces 96 and 97. Again, these cuts are carcfully aligned and oriented with respect to each other so that the fibers which are segregated into an annular ring 102 include the same fibers at both ends of the bundle while leaving the remaining fibers in undisturbed relation in the end faces 96, 97. Adjacent to the end 96, the anniilar fiber ring 102 is readily split into relatively small axially extending segments. A solvent such as acetone may then be added to these segments to reduce the viscosity of the set resin so that the fibers in these segments can slide relative to one another when they are bent. The segments may then `he readily peeled back axially along the fiber bundle and then brought together on one side of the image-carrying portion '103 of the bundle to form a generally cylindrical rod-like extension 104. The end portions of the glass fibers in the rodlike extension 104 are held together in clilmps by the resin which was cured prior to the removal of the fibers from the winding drtim. Additional resin or other suitable adhesive is applied to these end portions which are then bonded together and shaped to provide an end face suitable for receiving light.

The light and image-transmitting bundle is processed as has already been described to remove the unpolymerized resin. As before, the fiber bundle may be encased in a protective sheath wherein the loose fibers are immersed in a suitable lubricating fluid. After the end faces have been optically polished, light from a suitable source may be projected onto the end face of the rod-like member 104 and this light is conducted along the annular array of fibers 102 to illuminate a field of view adjacent to the end face 9.7. Light reflected by the field is conducted back alongl the fibers of the image-conducting portion 103 of the bundle to form an image of the field which may be viewed directly on the end face 96'. lf desired, various lens Systems may be utilized at the ends of the image carrying portion 96 to facilitate visualization of a desired area.

The forming and shaping of' the optical image fiber bundles is preferably carried out. as was described in connection with FIGURES 8 and 9, while the resin on the fibers intermediate the cured sections 92 is sufficiently set so that the individual fibers cannot move relative to one another. However, if desired, the fibers between the bonded end portions may be freed of the unpolymerizcd resin and then dried before being conformed to the dcsired shape and configuration. In this condition the bun die is anchored by means of molds or clamps and then impregnated with an adhesive oF sufficiently low viscosity to penetrate completely throughout the fibers where they are to be bonded and maintained in fixed relation.

Extremely thin optical fiber bundles may also be provided. When such thin fiber bundles as about .02 in thickness are desired having a greater width, a sufficient number of layers of the fiber maybe formed on the winding drum so that the combined depth of all of the layers on the drum conform to the desired thickness, about .02. The liber layers are removed from the winding drum and processed as before except as will now be described. The liber layers are laid down on the drum to a depth of .02 and after having been treated as described, the mass is removed together with the underlying sheet 6l), preferably of .00025 plastic as has been described, which is retained with the fibers adhered thereto to increase the strength of the bundles to be formed. This is then cut into strips of the desired widths which may be then shaped or molded as desired. To facilitate this shaping or mold ing, the resin anchoring material sprayed onto the fiber layers while they are being wound may have sufficient solvent added to its so that the resulting bundles are pliable. Additional solvent may be added to the fiber bundle strips before they are shaped. The unpolymerized resin may be removed from intermediate the ends of the bundles or the resin may be cured throughout to provide rigid optical ber bundles.

For example, a suitable width of such a thin strip of fibers may be rolled to form an annular hollow light carrier 106. If desired, the light carrier 106 may be cylindrical from end to end, or as shown in FIGURE 10, it may be formed with a rod-like portion 107 in which the fIbers are brought together to form a solid end face 108, leaving an opening 109 on the axis of the bundle 106 through which a viewing device may be inserted and dis posed axially. After being shaped, the unpolymcrizcd resin in the bundle 106 may be cured to provide a rigid structure.

Solid optical bundles may also be formed from the very thin thickness of glass libers supported on the plastic sheet. For example, the sheet of libers and plastic may be rolled or folded to form desired cylindrical, rectangular or other solid shapes. The tendency of the bonded end sections to fracture parallel to rather than through the glass libers facilitates such shaping, and when necessary, the end portions may be readily bonded to secure them in place. After the desired shape has been achieved the unpolymerized resin may be cured to provide a rigid bundle.

It is to be noted that while epoxy resins have been Vfound to be best suited for use in carrying out the process ot the present invention and in providing the best re suits in shaping and forming the optical liber bundles, other adhesives which ,may be either thermoplastic or thermo setting may be utilized.

The terms and expressions which, have been employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various moditications are possible within the scope of the invention claimed.

What is claimed is:

1. The method of making an image and 1ight-conducting liber optic device having a large number of extremely thin light-conducting coated glass fibers arranged at their ends in sidebyside aligned relation, which comprises (l) laying down a plurality of strands of flexible coated glass liber in substantially side-by-side aligned relation to form a layer, (2) applying an adhesive fluid to said layer, repeating steps 1 and 2 to form a plurality of superposed glass ber layers while allowing said adhesive throughout said layers progressively to set sufficiently to hold the glass fiber strands and the layers formed thereby in substantially immovable relation one to another, cutting the thus formed adhcsively united layers substantially parallel to the glass liber whereby `to form a bundle containing a plurality of aligned glass fibers extending in substantially side-byside and superposed relation with the glass libers held by said adhesive in substantially im movable relation and with the opposite ends of said libers forming the opposite end walls of said bundle, freeing the end portions of an array of said glass fibers at one end ot said bundle from the remainder of said glass fibers, and gathering said freed end portions together on one side of said bundle and adhesively uniting the same to form a third end wall adjacent to one end of said bundle, whereby light incident on said third end wall is conducted to the opposite end of said bundle along said array of glass fibers.

2. The method of makingan image and light-conductd ing liber optic device having a large number of extremely thin light-conducting coated glass libers arranged at their ends in side-by-side aligned relation, which comprises (l) laying down a plurality of coated flexible glass tiber strands in substantially sidc-byside aligned relation about a drum to form a layer, (2) applying a polymerizable resin bearing liquid to said layer in an amount small enough so that the surface tension of said liquid serves to draw the glass libsr strands in said layer together, repeating steps l and 2 to form a plurality of superposed glass liber layers about said drum while allowing said resin to set progressively throughout the thus formed succession of superposed layers, said resin setting suflicicntly lo form said' layers into a substantially rigid mass with the glass fiber strands thereof anchored in substantially immovable relation, polymerizing said resin along at least one strip extending transversely of said glass ber strands in said layers, cutting through said layers along said polymerized strip, removing said layers from said drum as a` .substantially rigid mass, cutting said mass ol layers substantially parallel to said glass flber strands to form a substantially rigid liber glass bundle in which the opposite end portions of the glass fiber strands are bonded together by the polymerized resin and the remainder of said glass libers are held together by the set resin, the opposite end walls of said bundle being formed by thc opposite ends of said glass liber strands, freeing the end portions of an annular peripheral array of said glass liber strands at onc end of i said bundle from the remainder of said glass liber strands, gathering said freed end portions together on one side of said bundle and bonding the same to form a third end wall adjacent to one end of said bundle, whereby light incident on said third end wall is conducted to tbe opposite end of said bundle along said annular array of glass fibers, and removing theset resin from said bundle to free said glass liber strands intermediate their bonded end portions.

3. The method of mailing a light-conducting liber optie device having a large number ol extremely thin lightconducting coated glass libers arranged at their ends in side-by-side aligned relation, which comprises (l) laying down on a plastic sheet having a thickness which is small compared to that of said libers a plurality of strands of llexible glass liber in substantially side-by-side relation to form a layer on said sheet, (2) applying an adhesive fluid to said fiber glass in an amount small enough so that the surface tension of said adhesive fluid serves to draw the glass liber strands in said layer together, and repeating steps l and 2 to form a plurality of superposed glass fiber layers on said sheet while allowing said ad- .hesive to set progressively throughout said layers to hold the glass fiber strands and the layers formed thereby together to said sheet, forming said sheet with said layers adhered thereto into a hollow cylinder with the fibers forming said layers extending axially along thc exterior thereof, gathering and bonding the end portions of said libers together adjacent to one end ot said cylinder while leaving the axis of said cylinder unobstructed to form a solid end wall, whereby light incident upon said end wall is conducted along said hollow cylinder to the opposite end thereof to provide an annular light source.

4. In an apparatus for making a light-conducting optic device made up of a large number ot' extremely thin lightconducting coated fibers arranged at their ends in sideby-side aligned relation, means for aligning a plurality of strands of liexible ligl|t-condueting coated liber in Sidcby side and superposed relation whereby to :form a plurality of superposed layers with the fiber strands in cach layer in side-'byside relation, means for applying an adhesive fluid to said fiber strands in each of said layers simultaneously as each of said layers is formed, and means for accelerating the setting rate of said adhesive fluid along preselected portions of said layers while said layers are being formed so as to bond the portions of said libers in said preselected portions in substantially rigid immovable relation one to another.

5. In an apparatus for making a light-,conducting optic device made up of a large number of extremely thin lightconducting coated glass fibers arranged at their ends in side-by-side aligned relation, means for forming a supply of hot glass, a rotatably mounted drinn, a carriage adjacent to one side of'said drum and movable axially relative thereto, means mounted on said carriage for guiding a flexible coated glass fiber from said supply to said drum, means for rotating said drum and for shifting said earriage axially in synchronism therewith whereby to form a succession of superposed layers of coated glass fiber strands about said drum with the strands of each layer in sidc-by-side aligned relation. and means movable with said carriage adjacent to the opposite side of said drum for applying an adhesive fluid to the glass liber strands of each of said layers simultaneously as each of said layers is formed, and means for accelerating the setting rate of said adhesive fluid along preselected portions of said layers while said layers are being formed so as to bond the portions of said fibers in said preselected portions in substantially rigid immovable relation one to another.

6. In an apparatus for mal-:ing a light-conducting optic device made up of a large number of extremely thin lightconducting coated glass fibers arranged at their ends in side-by-side aligned relation, means for forming a supply Aof hot glass, a drum and means for rotating tbe same, a

transfer roll, means supporting said transfer roll adjacent and substantially parallel to said drum with said transfer roll displaceable about said drum, means for rotating said transfer roll at a peripheral speed equal to that of said drum and including a rotatable member swingably connected to said transfer roll for running engagement with the peripheral surface of said drum, a carriage adjacent to said drum and movabie axially relative thereto, means including a guide member mounted on said carriage for guiding a flexible coated glass fiber from said supply to said drum when said carriage is moved in one direction and for guiding said glass fiber from said supply to said transfer roll when said carriage is moved in the opposite direction said guide member being displaceable between two extreme positions one adjacent to said drum and the other removed therefrom, means for moving said carriage in said one direction in synchronism with the rotation of said drum whereby to form a succession of superposed layers of coated glass fiber strands about said drum with the strands of each layer in side-by-side aligned relation and with all of said strands having the sante direction of advance relative to said drum, said transfer roll being displaceable about said drum toward and away from said guide member whereby said transfer roll is engageable with said glass liber when said guide member is in its said other position, means for moving said carriage in said opposite direction while said glass fiber isv guided to and wound about said transfer roll, means for applying an adhesive tiuid tothe glass liber strands of each of' said layers simultaneously as cach of said layers is formed.

7. In an apparatus aligning a very large number of extremely thin light-conducting coated glass fiber strands in side-by-side and superposed relation for making a lightconducting optie device made up of a large number of extremely thin light-conducting coated glass fibers arranged at their ends in side-by-side aligned relation, a winding drum, said drum having a thermally noncondnctive coating extending over its peripheral surface, a plurality of spaced heating elements carried by said thermally nonconduetive coating and thermally insulated thereby from the remainder of said drum, and said heating elements extending axialiy relative to said drum along said thermally nonconductivc coating. l

S. in an apparatus for making a light-conducting optic eevice made up of a large number of extremely thin lightconducting Coated glass fibers arranged at their ends in side-by-side aligned relation, means for heatingglass, means for supporting and feeding a `glass rod to said glass heating means, means for supporting about said rod a glass tube of a lower refractive index than said rod and for feeding said tube to said glass heating means, means for selectively varying the rate at which said tube is fed relative to said rod, a rotatably mounted drum. a carriage adjacent to said drum and movable axially relative thereto,

means mounted on said carriage for guiding a flexible glass fiber drawn from said glass heating means to said drum, means for rotating said drum at a speed in relation to the temperature and rate of feed of said rod and tube such that said glass fiber is drawn with a substantially constunt diameter and has a core formed of glass from said rod and a coating over the entire surface of said core formed of glass from said tube, means for shifting said carriage axially in synchronism with the rate of rotation of said drum whereby to form a succession of superposed layers of glass ber with the strands of glass fiber in each layer in side-by-side aligned relation, means for applying an adhesive fluid to the glass fiber strands of each of said layers` and means for adjusting the rate at which said ad bcsive fluid is fed.

9. In an apparatus for making a light-conducting optic device made up of a large number of extremely thin lightconducting coated glass fibers arranged at their ends in side-by-side aligned relation, a furnace, means for supporting and feeding a plurality of glass rods to said furnace, means for supporting and feeding to said furnace a plurality of glass tubes one about each of said rods and having a lower refractive index than said rods, a rotatably mounted drum, a carriage adjacent to said drum, means mounted on said carriage for guiding a plurality of flexible glass coated glass fibers one from each pair of said rods and tubes from said furnace to said drum, cach ol" said fioers having a core formed of glass from one of said rods and a coating over the entire surface of said Core formed of glass from one of said tubes, means for rotating said drum and for shifting said carriage axially in synehronism therewith whereby to form a succession of supcrposed layers of glass fiber strands about saidV drum with the strands of each layer in side-by-sidc aligned relation, and means for applying an adhesive fluid to the glass fiber strands of each of said layers simultaneously as each of said layers is formed.

l0. ln an apparatus for mal-:ing a light-conducting optic device made up of a large number of extremely thin lightconducting coated glass fibers arranged at their ends in side-by-side aligned relation, a furnace, means for stipporting and feeding a plurality of glass rods to said furnace, means for supporting and feeding to said furnace a plurality of glass tubes one about each of said rods and having a lower refractive index than said rods, a rotatably mounted drun., a carriage adjacent to said drum, means mounted on said carriage for guiding a plurality of flexible glass coated glass fibers one from each pair of said rods and tubes from said furnace to said drum, each of said fibers having a core formed olv `glass from one of said rods and a coating over the entire surface of said core formed of' glass from one of said tubes, means for rotating said drum and for shifting said carriage axially in synchronism therewith whereby to form a succession of superposed groups of layers of glass fiber strands about said drum with the layers of each of said groups being formed simultaneously in supcrposed relation and with the strands of each layer in sidc-by-side aligned relation, and means for applying an adhesive llnid to the glass liber strands of each of said layers simultaneously as et h ot' said layers is formed.

It. ln an apparatus for making a light-continuing optie device made up of a large number of extremely thin lightconducting coated fibers arranged at their ends in side-byside aligned relation, means including a rotatable drum for winding a plurality of strands of flexible light-conducting coated fiber in side-byside and superposed relation whereby to form a plurality of snperposcd layers with the fiber strands in each layer in side-by-side relation, means for applying an adhesive fluid to said fiber strands in each of said layers simultaneously as each of said layers is formed, means for winding each succeeding layer about said drum with the same direction of advance as the layer preceding the same, and means for accelerating the setting rate of said adhesive uid along preselected portions of said layers while said layers are being formed so as to bond the poi'- tions of said fibers in said preselected portions in substantially rigid immovable relation one to another.

12. The method of making light-conducting liber opties devices having a large number of extremely tliin |ightconducting coated glass fibers arranged at their ends in sidebyside relation, which comprises the steps of drawing glass liber from a supply of hot glass and forming a pluralit)r of superposed layers with the #glass fiber in each layer extending in substantially side-by-side relation, applying an adhesive material to thc glass ber to substantially the entire extent of said glass liber in each of .said layers while said layers are being formed, accelerating the setting rate of said adhesive material along preselected portions of said layers while said layers are being formed `so as to bond the portions of said fibers in said preselected portions in substantially rigid immovable relation one to another while allowing the remainder of said adhesive material to set sufiiciently to hold together the remainder of said glass fiber forming said layers.

13. The method as set forth in claim 12 which further comprises using a polymerizable resin-bearing liquid as said adhesive material.

14. The method of making light-conducting fiber optics devices having a large number of extremely thin light-conducting coated glass tibers arranged at their ends in side-by-side relation, which comprises the steps of drawing glass fiber from a supply of bot glass and forming a plurality of superposed layers with the glass fiber in each layer extending in substantially side-by-side relation, applying an adhesive material to the glass fiber to substantially the entire extent of said glass fiber in each of said layers while said layers are being formed, accelerating the setting rate of said adhesive material along preselected portions of said layers while said layers -are being formed so as to bond the portions of said fibers in said preselected portions in substantially rigid inimovable relation one to another while allowing the remainder of said adhesive material to set sutheiently to hold together the remainder of said glass fiber forming said layers, cutting the thus formed adhesively united glass fiber layers substantially parallel to the glass fiber whereby to form a strip containing a multiplicity of glass fibers held together along their entire length in substantially side-by-side and siiperposed relation, and then removing the adhesive from said glass bers in said strip except in said preselected portions whereby to fr ee the fibers intermediate said preselected portions.

15. The method of making light-conducting fiber .optics devices having a large number of extremely thin flight-conducting coated glass fibers arranged at their ends in side-by-sidc relation, which comprises the steps of drawing glass ber from a supply ol hot glass and forming a plurality of superposed layers with thc glass fiber in each layer extending in substantially side-by-side relation, applying an adhesive material to the glass fiber to substantially the entire extent ot' said glass fiber in each of said layers while said layers are being formed, accelerating the setting rate of said adhesive material along preselected portions of said layers extending transversely to said bers while said layers are being formed so as to bond the portions ot' said fibers in said preselected portions in substantially rigid immovable relation one to another while allowing the remainder of said adhesive material to set sufficiently to hold together the remainder of said glass fiber forming said layers, cutting said layers along at least one preselected portion trans verse to said fibers, cutting the'thus formed adhesively united glass fiber layers substantially parallel to the glass ber whereby to form a strip containing a multiplicity of glass fibers held together along their entire length in `substantially side-by-side and superposed relation, and

then removing the adhesive from said glass fibers in said strip except in said preselected portions whereby to free the fibers intermediate said preselected portions.

16. The method of making liglit-condiieting liber optics devices having a large niimher ot extremely thin light-conducting coated glass fibers arranged :it their ends in side-byside relation, which comprises the steps of drawing glass fiber from a supply of hot glass and forming a plurality of supcrposed layers with the glass tiber'in each layer extending in substantially siile-by-sitle relation, applying an adhesive material to thc glass fiber to substantially the entire extent of lsaid glass liber in each of said layers while said layers are being formed, accelerating the setting rate of said adhesive material along preselected portions of said layers extending transverscly to said fibers while said layers are being formed so as to bond the portions of said tibers in said preselected portions in substantially rigid immovable relation one to another while allowing the remainder ot said adhesive material to set suflieiently to hold together the remainder of said glass fiber forming said layers, cutting.

f plicity of glass fibers held together along their entire length in substantially side-byside and superposed relation, removing selected ones of the glass bers extending along said strip to modify the shape thereof, and then removing the adhesive trom said glass bers in said strip except in said preselected portions whereby to free the fibers intermediate said preselected portions.

17. The method of making light-conducting ber optics devices having a large number of extremely thin light-conducting coated glass tibers arranged at their ends in side-by-side relation, which comprises the steps of drawing a plurality of glass fibei's from a supply of hot glass and forming a plurality of siiperposcd layers one for each of said tibers with the glass fiber in each layer extending in substantially side-by-sidc relation, applying an adhesive material to the glass fiber to substantially the entire extent of said glass ber in each of said layers while said layers are being formed, and accelerating the setting rate of said adhesive material along preselected portions of said layers while said layers are being formed so as to bond the portions of said fibers in said preselected portions in substantially rigid immovable relation one to another while allowing the remainder of said adhesive material to set sufliciently to hold together the remainder of said glass fiber formingstiid layei's.

18. In an apparatus for aligning a very large number of extremely thin light-conducting coated glass fiber strands in side-by-side and superposed relation for making a light-conducting opties device made up of a large number of extremely thin lighteonducting coated glass ,fibers arranged at their ends in side-by-side aligned relation, a winding drum, said drum having a thermally nonconductive coating extending over its peripheral surface, a plurality of spaced heating elements carried by said thermally noncoiidiictive coating and thermally insulated thereby from the remainder of said drum, said heating elements extending axially relative to said drum along said thermally nonconductive coating, and means for selectively energizing said heating elements.

19. The method of making a light-conducting fiber optics device having a large number of extremely thin light-conducting coated glass fibers arranged in sideby side aligned relation, which comprises laying down on a plastic sheet having a thickness which is small compared to that of said fibers a plurality of strands of ilexible light-conducting coated glass fibers in substantially side-by-side relation to form a plurality of siiperposed layers of said fibers on said sheet, applying an adhesive fluid to said fibers in said layers substantially simultaneously as said layers are formed on said sheet, and

21 Z2 shaping said sheet with s'aid liber layers thereon nclud- 2,525,260 3/1958 OBrien 18S-1 ing gathering and bonding in compact substantially rigid 2,943,968 7/1960 Freeman et al. lad-91) immovable relation the end portions of said fibers ad- 3.ll33,73l 5/1962 Cole 156-175 jacent one end of said sheet to form a solid end wall so 3,l(l4,l9l 9/I963 Hicks el al. l56--l74 that light incident upon said end wall is conducted along 5 3,134,704 5/1964 Modigliani 156-167 said fibers to the other ends thereof. 3.143,102 9/1964 Erflkins et al. 156-181 References Cilcd by the Examiner EARL M. BERGERT, Primary Examiner.

UNITED STATES PATENTS E. S. ANDERSON, Examiner. 2,656,873 10/1953 sic/plums i 156-167 10 2,699,415 1/1955 Nachlmzm 156-173 nutren stares PATENT orrien CElTllilCi/t'l @il CdllliECTlUN Patent No 3 256 ,710 February Z2 1966 Lawrence E, Curtiss 1t is herebyv certified that error appears in the above numbered patent requiring correction and that the said Letters Patent Should read as corrected below.

ln the grant lines l and 13 and in the heading to the printed specification, lines 6 and 7 for "Wilbur Peters", each occurrence, read C. Wilbur Peters Column 7, line 21, for "exible" read -e flexible ;V line 69, after "14" insert iscolumn 8 line 37 for "systems" read system line 54 for "alingned" read aligned line 55 for "Carriage" read Carriage Column 14 line 74 for "its" read it column 16, line 46, before "to" insert and H Column 17, line `52., after "apparatus" insert for Signed and sealed this 11th day of July 1967.

(SEAL) Attest:

ERNEST w. swiDER EDWARD J, BRENNER Attestlng Officer Commissioner of Patents 

12. THE METHOD OF MAKING LIGHT-CONDUCTING FIBER OPTICS DEVICES HAVING A LARGER NUMBER OF EXTREMELY THIN LIGHT-CONDUCTING COATED GLASS FIBERS ARRANGED AT THEIR ENDS IN SIDEBY-SIDE RELATION, WHICH COMPRISES THE STEPS OF DRAWING GLASS FIBER FROM A SUPPLY OF HOT GLASS AND FORMING A PLURALITY OF SUPERPOSED LAYERS WITH THE GLASS FIBERS IN EACH LAYER EXTENDING SUBSTANTIALLY SIDE-BY-SIDE RELATION, APPLYING AN ADHESIVE MATERIAL TO THE GLASS FIBER TO SUBSTANTIALLY THE ENTIRE EXTENT OF SAID GLASS FIBER IN EACH OF SAID LAYERS WHILE SAID LAYERS ARE BEING FORMED, ACCELERATING THE SETTING RATE OF SAID ADHESIVE MATERIAL ALONG PRESELECTED PORTIONS OF SAID LAYERS WHILE SAID LAYERS ARE BEING FORMED 